![\"Typical](\"http:\/\/powerquality.sg\/wordpress\/wp-content\/uploads\/2023\/10\/typical-datasheet-ITHD-3-percent.png\")
<\/a><\/figure>\n\n\n\nIn Singapore, for a Grid-Tied Solar PV connection, the Licensed Electrical Worker (LEW) (i.e Qualified Person) will have to submit the inverter’s PQ-related type test report to the Grid operator (SP Group). Below is one such example – here it shows the portion whereby the inverter was tested as part of the UK Engineering Recommendation G99 test requirements. Values stated for quality-brand inverters will have its harmonic current emission values well within the limits.<\/p>\n\n\n\n You may wonder – One inverter is ok but how about a number of them accumulatively? I had the opportunity to measure numerous sites whereby the rated PV output was accumulatively more than 1MWac. <\/p>\n\n\n\n Here are two sites whereby the background harmonics can be considered to be on the low side and as such the effects of the on-site inverters were more representative (limited ‘contributions’ from the localized electrical network). <\/p>\n\n\n\n All measurements were done using an IEC 61000-4-30 Class A certified Power Quality instruments. <\/p>\n\n\n\n The Current Harmonic Distortion (ITHD) in the trends below have been scaled to the respective aggregated inverters’ rated current (in other words, shown here as Total Demand Distortion (TDD) values).<\/p>\n\n\n\n As observed here, the TDD values were less than 3% and the sinusoidal shape of the current waveforms were very much still visible.<\/p>\n\n\n\n Note: IEEE 519 recommends TDD values of 5% for power generation facilities.<\/p>\n\n\n\n Site #1:<\/strong><\/p>\n\n\n\n Premises Type: Warehousing \/ logistics Site #2: <\/strong><\/p>\n\n\n\n Premises Type: Solar Farm (On-site loads: Auxiliary power and lighting loads only) <\/p>\n\n\n\n In general, current harmonics contribution from solar PV inverters do not pose much of a power quality problem. Its ITHD is usually small and negligible as compared to a harmonics-producing load such as a variable speed drive (ITHD for a typical 6-pulse drive ranges between 30% – 50%). Typically, one will find a Current Total […]<\/p>\n","protected":false},"author":1,"featured_media":777,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_newsletter_tier_id":0,"jetpack_publicize_message":"","jetpack_is_tweetstorm":false,"jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false}}},"categories":[9,5,13],"tags":[],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/powerquality.sg\/wordpress\/wp-content\/uploads\/2023\/10\/pv-solar.png","jetpack_shortlink":"https:\/\/wp.me\/p41TEZ-cg","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/powerquality.sg\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/760"}],"collection":[{"href":"https:\/\/powerquality.sg\/wordpress\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/powerquality.sg\/wordpress\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/powerquality.sg\/wordpress\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/powerquality.sg\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=760"}],"version-history":[{"count":14,"href":"https:\/\/powerquality.sg\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/760\/revisions"}],"predecessor-version":[{"id":790,"href":"https:\/\/powerquality.sg\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/760\/revisions\/790"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/powerquality.sg\/wordpress\/index.php?rest_route=\/wp\/v2\/media\/777"}],"wp:attachment":[{"href":"https:\/\/powerquality.sg\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=760"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/powerquality.sg\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=760"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/powerquality.sg\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=760"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}<\/a><\/figure>\n\n\n\n
PV Size: 1352.8 kWp
Aggregated Inverter(s) Rated Current = 1613A @ 400V.
Measurement Point: 2500A PV-AC DB, directly connected to the Premises 5000A Main Switchboard (served by a 3MVA transformer) via 3000A flexible CTs (clamped on 3 sets of 500sqmm cables per phase).
CT direction towards MSB as Load, PV as Source.
VTHD: 0.89% – 3.96% (CP95: 3.6%).<\/p>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a><\/figure>\n\n\n\n
PV Size: 2652kWp (for CS1)
Aggregated Inverter(s) Rated Current = 62A @ 22kV (for CS1).
Solar inverters connected at 400V, stepped-up to 22kV via a 2.5MVA transformer.
Measurement Point: 22kV Incomer 1 from PowerGrid (CS1) via VT and CT.
Note: Solar Farm has 2 x 22kV intakes from PowerGrid – only one intake shown here.
CT direction towards PV as Load.
Solar Farm was connected to a Lightly-loaded 22kV distribution network.
VTHD: 0.59% – 1.22% (CP95: 1.09%).<\/p>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a><\/figure>\n","protected":false},"excerpt":{"rendered":"